Although also applicable to any desired closures, the present invention and also the set of problems on which it is based are discussed in more detail below with reference to a closure for a container filled with an adhesion promoter composition.
Adhesion promoters are substances which improve the adhesion, more particularly of adhesives and sealants, to surfaces on which bonding or sealing, respectively, is to take place. Compositions comprising adhesion promoters (adhesion promoter compositions) are typically produced by manufacturers in the chemical industry and supplied more particularly to customers from the automotive industry, for the purpose, for example, of the adhesive bonding of windscreens.
Accordingly there are essentially two requirements imposed on a closure of this kind:
The first requirement is to seal the container, filled with an adhesion promoter composition, during transport from the manufacturer to the customer and during its storage, in other words to prevent emergence of adhesion promoter composition from the container. During transport, and/or during storage, a pressure referred to as stacking pressure is exerted, as a result of the stacking of two or more such containers on top of one another, on containers located further down. Furthermore, with adhesion promoter compositions of this kind which contain a volatile solvent, a gas pressure is built up in the container over a relatively long time during transport, and/or during storage. Both the stacking pressure and the gas pressure are comparatively high, which means that the closure must have a high sealing effect in order to prevent emergence of the adhesion promoter composition.
The second requirement is to seal the container between applications of the adhesion promoter at the customer's premises. Application of the adhesion promoter to, say, a windscreen takes a few seconds. The container with the adhesion promoter is then put down until, a few minutes later, a further windscreen is ready for the application of the adhesion promoter composition. Between applications, the closure ought in particular to prevent emergence of the adhesion promoter composition if the container is accidentally knocked over, and to prevent emergence of the volatile solvent and the ingress of atmospheric moisture.
One prior art known to the applicant envisages a closure which has a cup and a screw cap. The cup is inserted into an opening to be closed, which is the opening of a pipe-like spout of a container, after which the screw cap is screwed onto an external thread of the spout and, in the course of this operation, presses the cup into the opening, as a result of which this opening is closed in a fluid-tight manner.
With the closure known to the applicant, the actuation of the closure prior to the application of the adhesion promoter composition, in other words the opening of the closure, and after the application of the adhesion promoter composition, in other words the closing of the closure, is very inconvenient since, on the one hand, the screwing and unscrewing of the rotating cap takes a comparatively long time and, on the other hand, the insertion and extraction of the cup represents a further comparatively time-consuming handling operation, requiring considerable coordination of both hands of the user.